Migrates QUIC sessions to a new network when old network is (about to be) disconnected.

net/base/network_change_notifier.cc

Index: net/base/network_change_notifier.cc
diff --git a/net/base/network_change_notifier.cc b/net/base/network_change_notifier.cc
index 187923cc8969d06230b55d8166d2eb041665b8a0..33f2d4516c04e5b1e611f021110bbc9c3f9d7de0 100644
--- a/net/base/network_change_notifier.cc
+++ b/net/base/network_change_notifier.cc
@@ -922,6 +922,16 @@ void NetworkChangeNotifier::NotifyObserversOfNetworkChangeForTests(
 }
 
 // static
+void NetworkChangeNotifier::NotifyObserversOfSpecificNetworkChangeForTests(
+    NetworkChangeType type,
+    NetworkHandle network) {
+  if (g_network_change_notifier) {
+    g_network_change_notifier->NotifyObserversOfSpecificNetworkChangeImpl(
+        type, network);
+  }
+}
+
+// static
 void NetworkChangeNotifier::NotifyObserversOfInitialDNSConfigReadForTests() {
   if (g_network_change_notifier)
     g_network_change_notifier->NotifyObserversOfInitialDNSConfigReadImpl();